Current methods for crosslinked polyolefin synthesis include a first method which involves grafting of silane moieties on the high molecular weight polymer using reactive extrusion and subsequent curing of silane groups by moisture curing in the presence of a suitable catalyst. Synthesis of copolymer of olefin and vinyl silane are also reported. However, in both cases high molecular weight polymer needs to be extruded into the end use article and then moisture cured to generate Si—O—Si linkages. The moisture curing is a very slow process taking several hours to days. The diffusion of moisture limits the thickness and shape of the end use article.
A second method involves the extruding the high molecular weight polyolefin into the end use article which is then irradiated with high energy electron beam. The electron beam creating reactive sites on the polymer chains which then couple to generate crosslinks. The electron beams are expensive and penetration of the beam once again limits the thickness and shape of end use article.
A third method involves generation of crosslinks using free radicals produced by dissociation of organic molecules such as peroxides. These organic molecules are added to the high molecular weight polymer during extrusion and the end use article is formed. Subsequent heating of the article helps dissociation of the small organic molecule into free radicals which then generate active sites on the polymer capable of coupling to form crosslinks. However, it is not always easy to delay the dissociation of peroxides until the shape of the article is given. Premature decomposition and subsequent prolonged attempts at thermally shaping the polymer can result in a phenomenon called “scorching”.
In all three processes, a common factor is the extrusion of high molecular weight polymer which is an energy intensive operation. The present invention is related to the synthesis of high molecular thermoset polyolefin from low molecular weight waxes with very low viscosities. The low viscosity implies relatively large size articles and intricate designs could be produced with less energy. Fast reaction rates of anhydride and amines would result in fast curing of the product. Finally, the presence of functional groups on the polyolefin wax and diamines would facilitate the insertion of any inorganic reinforcements into such thermosets.
Therefore, it would be very advantageous to produce polyolefin (polyethylene, polypropylene and their copolymers) crosslinked thermosets using maleic anhydride functionalized polyolefin waxes, obtained by using metallocene or Zeigler Natta catalysts, with alkyl and alkyl ether diamines.